The embodiments of the present disclosure generally relate to aqueous-based treatment fluids that can be crosslinked while simultaneously acting as friction reducers.
Aqueous treatment fluids can be used in a variety of subterranean treatment operations. Such treatment operations can include, without limitation, drilling operations, stimulation operations, production operations, sand control treatments, and the like. As used herein, the terms “treat,” “treatment,” “treating,” and grammatical equivalents thereof refer to any subterranean operation that uses a fluid in conjunction with achieving a desired function and/or for a desired purpose. Use of these terms does not imply any particular action by the treatment fluid or a component thereof, unless otherwise specified herein. Illustrative treatment operations can include, for example, drilling operations, fracturing operations, gravel packing operations, acidizing operations, scale dissolution and removal operations, sand control operations, consolidation operations, and the like.
Moreover, many treatments require fluids that have increased viscosity. For instance, viscous fluids that are free of particulates are often pumped into a portion of a subterranean formation to initiate fractures in downhole stimulation operations. Once the fractures are initiated, a viscous fluid loaded with particulates (commonly known as proppant) is inserted into the created fractures. The particulates act to hold the fracture faces apart (that is, they “prop open” the fracture) once the fracturing pressure is released.
Hydrocarbon-producing wells also may undergo gravel packing treatments, inter alia, to reduce the migration of unconsolidated formation particulates into the well bore. In gravel-packing treatments, a viscosified treatment fluid suspends particulates (commonly known as “gravel”) to be deposited in a desired area in a well bore, e.g., near unconsolidated or weakly consolidated formation zones, to form a gravel pack to enhance sand control. One common type of gravel-packing operation involves placing a sand control screen in the well bore and packing the annulus between the screen and the well bore with the gravel particulates of a specific size designed to prevent the passage of formation sand. The gravel particulates act, inter alia, to prevent the formation particulates from occluding the screen or migrating with the produced hydrocarbons, and the screen acts, inter alia, to prevent the particulates from entering the production tubing.
In some situations, fracturing and gravel-packing treatments are combined into a single treatment (commonly referred to as “frac-pack” operations). In such “frac-pack” operations, the treatments are generally completed with a gravel pack screen assembly in place with the hydraulic fracturing treatment being pumped through the annular space between the casing and screen. In this situation, the hydraulic fracturing treatment ends in a screen-out condition, creating an annular gravel pack between the screen and casing. In other cases, the fracturing treatment may be performed prior to installing the screen and placing a gravel pack.
In order to create aqueous viscosified fluids for use in various subterranean treatment operations, generally a hydratable gelling agent is added to an aqueous fluid. The act of hydration causes the aqueous fluid to gel and thus increases its viscosity. Often it is desirable to increase the treatment fluid viscosity above the level that can be achieved with gelling agents alone. In such cases, a crosslinker may be added to the fluid that causes the gelling agent molecules to crosslink with neighboring gelling agent molecules to further increase viscosity.
However, while the viscosity increases brought by gelling agents and crosslinking agents are desirable to increase solids loading capacity and hydraulic head, they can act to undesirably increase the energy losses causes by the friction of the non-viscous fluid traveling through wellbore equipment and subterranean formations. While external friction reduction agents are known and they can be added to treatment fluids, it is also known that they are not indicated for use with crosslinked fluids due to their tendency to compromise gel performance by negatively impacting the formation of crosslinks.